JP2016069629A - Aqueous pigment dispersion and production method thereof, coloring composition, ink composition, and inkjet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous pigment dispersion excellent in storage stability and a production method thereof, and a coloring composition, an ink composition, and an inkjet recording method using the aqueous pigment dispersion.SOLUTION: A production method of an aqueous pigment dispersion comprises: a step a for dispersing an azo pigment expressed by the formula 1 or tautomer thereof, and a first dispersant in water to acquire an aqueous pigment dispersion A; a step b for dispersing the azo pigment expressed by the formula 1 or tautomer thereof, and a second dispersant in water to acquire an aqueous pigment dispersion B; and a step c for mixing the aqueous pigment dispersion A and the aqueous pigment dispersion B to acquire an aqueous pigment dispersion.SELECTED DRAWING: None

Description

  The present invention relates to an aqueous pigment dispersion and a production method thereof, a coloring composition, an ink composition, and an inkjet recording method.

  In recent years, a material for forming a color image has been mainly used as an image recording material, and specifically, an ink jet recording material, a thermal transfer recording material, an electrophotographic recording material, a transfer halogen. Silver halide photosensitive materials, printing inks, recording pens, and the like are actively used. Further, a color filter is used for recording and reproducing a color image in an imaging device such as a charge coupled device (CCD) in a photographing apparatus and in a liquid crystal display (LCD) or a plasma display (PDP) in a display. In these color image recording materials and color filters, so-called additive color mixing and subtractive color mixing three primary colors (dyes and pigments) are used to display or record full color images.

Azo pigments are widely used in printing inks, ink compositions for ink jet recording, electrophotographic materials, and the like because they are excellent in hue and coloring power, which are color characteristics.
In various colored compositions, when a pigment is used as a colorant, it is important to ensure the dispersibility and dispersion stability of the solid pigment.
From the viewpoints of pollution prevention and occupational health, water-based industries are strongly oriented in industries that use colorants such as paints and printing inks. Further, stationery such as ballpoint pens and sign pens used for recording information, and recording liquids such as printers and plotters typified by ink jets are becoming water-based in terms of toxicity and hygiene.
Furthermore, in recent years, an aqueous dispersion in which a water-insoluble solid such as a pigment is dispersed has been widely used as an ink composition for ink jet recording.
As conventional pigment dispersions, those described in Patent Documents 1 and 2 are known.

JP 2011-46870 A JP 2011-74376 A

  The problem to be solved by the present invention is to provide an aqueous pigment dispersion excellent in storage stability and a method for producing the same, and a coloring composition, an ink composition, and an inkjet recording method using the aqueous pigment dispersion. is there.

The above-mentioned problems of the present invention have been solved by means described in the following <1>, <7> to <9>, <11> or <12>. It is described below together with <2> to <6>, <10> and <13> to <15> which are preferred embodiments.
<1> Step a in which an azo pigment represented by Formula 1 or a tautomer thereof, and a first dispersant are dispersed in water to obtain an aqueous pigment dispersion A, an azo pigment represented by Formula 1 or Step t for obtaining the aqueous pigment dispersion B by dispersing the tautomer and the second dispersant in water, and the aqueous pigment dispersion by mixing the aqueous pigment dispersion A and the aqueous pigment dispersion B A process for producing an aqueous pigment dispersion, comprising the step c of obtaining

<2> The method for producing an aqueous pigment dispersion according to <1>, wherein at least one of the first dispersant and the second dispersant is a polymer dispersant.
<3> The first dispersant is a dispersant having an amine value of 5 mgKOH / g or more and an amine value> acid value, and the second dispersant is a long-chain fatty acid salt or an acid value of 5 mgKOH / g or more. And the manufacturing method of the aqueous pigment dispersion liquid according to <1> or <2>, which is a dispersant having an acid value ≧ an amine value,
<4> The method for producing an aqueous pigment dispersion according to any one of <1> to <3>, including a step of performing heat treatment on the obtained aqueous pigment dispersion after step c.
<5> In the aqueous pigment dispersion obtained, the total content of the first dispersant and the second dispersant with respect to 100 parts by mass of the azo pigment represented by Formula 1 or a tautomer thereof Is a method for producing an aqueous pigment dispersion according to any one of <1> to <4>, which is 10 to 80 parts by mass,
<6> The method for producing an aqueous pigment dispersion according to any one of <1> to <5>, wherein the azo pigment represented by Formula 1 or a tautomer thereof is not subjected to salt milling. ,
<7> An aqueous pigment dispersion produced by the method for producing an aqueous pigment dispersion according to any one of <1> to <6>,
<8> A colored composition using, as a raw material, an aqueous pigment dispersion produced by the method for producing an aqueous pigment dispersion according to any one of <1> to <6>,
<9> An ink composition used as an aqueous pigment dispersion raw material produced by the method for producing an aqueous pigment dispersion according to any one of <1> to <6>,
<10> The ink composition according to <9>, which is an ink composition for inkjet recording,
<11> An ink jet recording method comprising a step of discharging the ink composition for ink jet recording according to <10> onto a recording medium by an ink jet method,
<12> an aqueous pigment dispersion characterized by containing an azo pigment represented by formula 1 or a tautomer thereof, a first dispersant, a second dispersant, and water,

<13> The aqueous pigment dispersion according to <12>, wherein at least one of the first dispersant and the second dispersant is a polymer dispersant,
<14> The first dispersant is a dispersant having an amine value of 5 mgKOH / g or more and an amine value> acid value, and the second dispersant is a long-chain fatty acid salt or an acid value of 5 mgKOH / g or more. And an aqueous pigment dispersion according to <12> or <13>, which is a dispersant having an acid value ≧ an amine value,
<15> The total content of the first dispersant and the second dispersant is 10 to 80 parts by mass with respect to 100 parts by mass of the azo pigment represented by Formula 1 or a tautomer thereof. The aqueous pigment dispersion according to any one of <12> to <14>.

  ADVANTAGE OF THE INVENTION According to this invention, the aqueous pigment dispersion excellent in storage stability, its manufacturing method, and the coloring composition, ink composition, and inkjet recording method using the said aqueous pigment dispersion can be provided.

Hereinafter, the present invention will be described in detail.
In addition, in this specification, description of "xx-yy" represents the numerical range containing xx and yy. Further, “a polymer having a basic functional group at at least one of the ends of the main chain” or the like is also simply referred to as “component A” or the like.
In the present invention, “mass%” and “wt%” are synonymous, and “part by mass” and “part by weight” are synonymous.
In the present invention, a combination of two or more preferred embodiments is a more preferred embodiment.
In the present specification, regarding the notation of the group in the compound represented by the formula, when there is no substitution or no substitution, the group can further have a substituent unless otherwise specified. In addition to an unsubstituted group, a group having a substituent is also included. For example, in the description of the formula, if “R represents an alkyl group, a cycloalkyl group, or an aryl group” is described, “R represents an unsubstituted alkyl group, a substituted alkyl group, an unsubstituted cycloalkyl group, a substituted cycloalkyl”. Represents a group, an unsubstituted aryl group or a substituted aryl group. In the present specification, (meth) acryl represents a concept including both acryl and methacryl, and the same applies to (meth) acrylate, (meth) acrylic acid, and the like.
Moreover, the polymer in this specification shall include a copolymer.

(Aqueous pigment dispersion and method for producing the same)
The aqueous pigment dispersion of the present invention (hereinafter also simply referred to as “pigment dispersion”) is an azo pigment represented by Formula 1 or a tautomer thereof (hereinafter simply referred to as “azo pigment represented by Formula 1”). And a first dispersant, a second dispersant, and water.
The method for producing an aqueous pigment dispersion of the present invention comprises the steps a, in which an azo pigment represented by formula 1 or a tautomer thereof, and a first dispersant are dispersed in water to obtain an aqueous pigment dispersion A. Step b in which the azo pigment represented by Formula 1 or a tautomer thereof and the second dispersant are dispersed in water to obtain an aqueous pigment dispersion B, and the aqueous pigment dispersion A and the aqueous pigment dispersion And c) to obtain an aqueous pigment dispersion by mixing with B.
The aqueous pigment dispersion of the present invention is preferably an aqueous pigment dispersion produced by the method for producing an aqueous pigment dispersion of the present invention.

<Azo pigment represented by Formula 1>
Hereinafter, the azo pigment represented by Formula 1 in the present invention will be described in detail.
In addition, the azo pigment represented by Formula 1 may be a salt, hydrate or solvate thereof.
The azo pigment represented by Formula 1 is a hydrate containing water molecules in the crystal, or a solvent (for example, alcohols such as methanol, ethanol, 2-propanol, t-butyl alcohol, acetone, methyl ethyl ketone, etc. A solvate containing ketones, aprotic solvents such as acetonitrile, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and toluene) may be used.

Regarding the azo pigment represented by Formula 1, tautomers such as Scheme 1 (for example, azo-hydrazone tautomers) and geometric isomers represented by Scheme 2 are also included in the present invention. Are included in these formulas. In addition, (t) C ₄ H ₉ represents a t-butyl group.

-Synthesis of azo pigment represented by Formula 1-
Below, the azo pigment represented by Formula 1 is compoundable by the method of Unexamined-Japanese-Patent No. 2010-159405, for example.
The obtained product can be used after being treated according to a post-treatment method of a normal organic synthesis reaction and then purified or not purified.
That is, for example, the product liberated from the reaction system can be used without being purified, or can be used alone or in combination for purification by recrystallization, salt formation or the like.
In addition, after completion of the reaction, it is opened in water or ice, and the operation of purifying the freed or extracted with organic solvent / aqueous solution without purification or by recrystallization, crystallization, salt formation, etc. alone or in combination Can also be served. Note that the reaction solvent may be distilled off in advance in water or ice, or may be put in water or ice without being distilled off. Furthermore, it may be neutralized after being put in water or ice, or may not be neutralized.

  The azo pigment represented by Formula 1 may be subjected to post-treatment as necessary. Examples of post-treatment methods include solvent salt milling, salt milling, dry milling, solvent milling, pigment particle control step by grinding treatment such as acid pasting, solvent heating treatment, resin, surfactant and dispersant. The surface treatment process by etc. is mentioned.

The primary particle diameter can be reduced by performing post-treatment such as solvent salt milling or salt milling. Therefore, in order to make the pigment particles into a more preferable form, it is preferable to perform solvent salt milling, salt milling or dry milling from the viewpoint of dispersibility and stability over time.
The method for producing the aqueous pigment dispersion of the present invention preferably does not perform such post-treatment, particularly solvent salt milling or salt milling. In the production method of the aqueous pigment dispersion of the present invention, an aqueous pigment dispersant having sufficiently excellent storage stability can be obtained without performing such post-treatment, so that the cost and the simplicity of the process can be obtained. Excellent.
Moreover, it is preferable that the azo pigment represented by Formula 1 in the aqueous pigment dispersion of the present invention is not subjected to salt milling.

-Solvent salt milling-
As solvent salt milling, for example, a crude azo pigment, an inorganic salt, and an organic solvent that does not dissolve the crude azo pigment are charged into a kneader and kneaded and ground therein. As said inorganic salt, water-soluble inorganic salt can be used conveniently, For example, it is preferable to use inorganic salts, such as sodium chloride, potassium chloride, sodium sulfate. Moreover, it is more preferable to use an inorganic salt having an average particle size of 0.5 to 50 μm.
The amount of the inorganic salt used is preferably 3 to 20 times by mass, more preferably 5 to 15 times by mass with respect to the crude azo pigment. As the organic solvent, a water-soluble organic solvent can be suitably used, and the solvent easily evaporates due to a temperature rise during kneading, so that a high boiling point solvent is preferable from the viewpoint of safety.

Examples of such organic solvents include diethylene glycol, glycerin, ethylene glycol, propylene glycol, liquid polyethylene glycol, liquid polypropylene glycol, 2- (methoxymethoxy) ethanol, 2-butoxyethanol, 2- (isopentyloxy) ethanol. , 2- (hexyloxy) ethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, dipropylene Glycol, dipropylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipro Glycol or mixtures thereof.
The amount of the water-soluble organic solvent used is preferably 0.1 to 5 times by mass with respect to the crude azo pigment. The kneading temperature is preferably 20 ° C to 130 ° C, particularly preferably 40 ° C to 110 ° C.
As a kneader, for example, a kneader or a mix muller can be used.

-Average primary particle diameter of the azo pigment represented by Formula 1-
When the primary particles of the azo pigment obtained by the above production method are observed with a transmission microscope, the length in the major axis direction is preferably 0.01 μm or more and 10 μm or less, and preferably 0.01 μm or more and 3 μm or less. Is more preferably 0.02 μm or more and 0.5 μm or less, particularly preferably 0.02 μm or more and 0.2 μm or less, and most preferably 0.02 μm or more and 0.15 μm or less. When it is in the above-mentioned range, high fastness to light and ozone is exhibited, the dispersibility is excellent, and the storage stability of the aqueous pigment dispersion is excellent.

  The total content of the azo pigment represented by Formula 1 and the tautomer thereof in the aqueous pigment dispersion of the present invention is preferably 0.1 to 30% by mass with respect to the total mass of the aqueous pigment dispersion. The content is more preferably 0.5 to 25% by mass, still more preferably 1 to 20% by mass, and particularly preferably 5 to 15% by mass.

  The volume average particle size of the azo pigment represented by Formula 1 in the aqueous pigment dispersion of the present invention is preferably 0.01 to 10 μm, more preferably 0.01 to 3 μm, and 0.02 More preferably, it is -0.5 micrometer, It is especially preferable that it is 0.02-0.2 micrometer, It is most preferable that it is 0.02-0.15 micrometer.

  The volume average particle diameter of the pigment refers to the particle diameter of the pigment itself or the particle diameter to which the additive has adhered when an additive such as a dispersant is adhered to the pigment. In the present invention, a Nanotrac UPA particle size analyzer (UPA-EX150; manufactured by Nikkiso Co., Ltd.) can be used as a measuring device for the volume average particle diameter of the pigment. The measurement can be performed according to a predetermined measurement method by placing 3 ml of the aqueous pigment dispersion in a measurement cell. As parameters input at the time of measurement, the viscosity of the pigment dispersion is used as the viscosity, and the density of the pigment is used as the density of the dispersed particles.

<First dispersant and second dispersant>
The aqueous pigment dispersion of the present invention contains a first dispersant and a second dispersant.
The first dispersant and the second dispersant in the present invention are not particularly limited except that they are different dispersants, but the first dispersant is a dispersant having an amine value of 10 mgKOH / g or more. More preferably, the dispersant is a dispersant having an amine value of 10 mgKOH / g or more and an amine value> acid value, and the second dispersant is a long-chain fatty acid salt or an acid value of 5 mgKOH. / G or more is preferable, and a long-chain fatty acid salt or a dispersant having an acid value of 5 mgKOH / g or more and an acid value ≧ an amine value is more preferable.

  The acid value in the present invention represents an acid value per 1 g of the solid content of the dispersant, and can be determined by potentiometric titration according to JIS K 0070. The amine value represents an amine value per 1 g of the solid content of the dispersant, and is a value converted to an equivalent of potassium hydroxide after being obtained by potentiometric titration using a 0.1N hydrochloric acid aqueous solution.

  The long chain fatty acid salt is preferably an alkali metal salt of a long chain fatty acid having 12 to 36 carbon atoms, specifically, sodium oleate, potassium oleate, sodium stearate, potassium stearate, sodium palmitate. And potassium palmitate. Among these, sodium oleate and sodium stearate are preferably exemplified.

The first dispersant is preferably a dispersant selected from the following group A, and the second dispersant is preferably a dispersant selected from the following group B.
Group A: EFKA 4510, EFKA 4560, EFKA 4580, EFKA 4585, EFKA 4800, EFKA 5071, EFKA 6220, DISPERBYK-183 and DISPERBYK-184
Group B: DISPERBYK-181, DISPERBYK-180, DISPERBYK-187, DISPERBYK-190, DISPERBYK-194, DISPERBYK-2090, DISPERBYK-2091, EFKA 4520, EFKA 6225, and long-chain fatty acid salts among these, particularly preferred first The dispersant is EFKA 4585, and a particularly preferred second dispersant is DISPERBYK-181, DISPERBYK-187, or DISPERBYK-190.
The EFKA (registered trademark) series is a dispersant manufactured by BASF, and the DISPERBYK (registered trademark) series is a dispersant manufactured by BYK Chemie.
The acid value and amine value of these commercial products are shown below.

The amine value of the first dispersant is preferably 10 to 150 mgKOH / g, more preferably 10 to 100 mgKOH / g, and still more preferably 13 to 50 mgKOH / g.
The first dispersant preferably has a difference between amine value and acid value (amine value-acid value) of 3 to 100 mgKOH / g, more preferably 5 to 70 mgKOH / g. More preferably, it is -40 mgKOH / g.

When the second dispersant is a dispersant having an acid value of 5 mgKOH / g or more, the acid value of the second dispersant is preferably 5 to 200 mgKOH / g, and preferably 6 to 150 mgKOH / g. More preferably, it is 15-70 mgKOH / g.
The second dispersant preferably has a difference between the acid value and the amine value (acid value-amine value) of 0 to 200 mgKOH / g, more preferably 0 to 150 mgKOH / g, More preferably, it is -100 mgKOH / g.

  Among them, the first dispersant having an amine value of 13 to 50 mgKOH / g and a value of (amine value-acid value) of 10 to 40 mgKOH / g, and an acid value of 15 to 70 mgKOH / g And the combination with the 2nd dispersing agent whose value of (acid value-amine value) is 0-100 mgKOH / g is especially preferable.

From the viewpoint of dispersibility and dispersion stability, it is preferable that both the first dispersant and the second dispersant are water-soluble dispersants.
The first dispersant and the second dispersant have a solubility in water of preferably 1 g / 100 mL or more, more preferably 3 g / 100 mL or more, and 5 g / 100 mL or more. Is more preferable. When the solubility in water is 1 g / 100 mL or more, the solubility in water is excellent, the adsorptivity to a specific pigment is excellent, and good dispersibility is obtained.
Further, from the viewpoint of the image quality of the printed matter, either the first dispersant or the second dispersant is preferably a polymer dispersant, and the first dispersant is at least a polymer dispersant. More preferably.
The polymer dispersant in the present invention is a dispersant having a weight average molecular weight of 1,000 or more.
In the present invention, the weight average molecular weight of the dispersant is preferably 5,000 or more and 200,000 or less, more preferably 8,000 or more and 150,000 or less, and 10,000 or more and 100,000 or less. More preferably it is. When the weight average molecular weight is 5,000 or more, the image quality of the printed matter is excellent. On the other hand, when the weight average molecular weight is 200,000 or less, it is possible to suppress an increase in viscosity and further prevent a decrease in storage stability.

  In the present invention, the weight average molecular weight of the compound is measured by a gel permeation chromatography method using a polystyrene standard or a polyethylene oxide standard. In addition, when there is a catalog value as the weight average molecular weight of the polymer dispersant, the catalog value can also be adopted.

In the present invention, the polymer dispersant preferably includes polyurethane, polyester, and / or polyvinyl resin, more preferably polyurethane, polyester, and / or polyvinyl resin, and is preferably a polyvinyl resin. Further preferred.
The polymer dispersant is preferably a dispersant obtained by polymerizing both a hydrophilic monomer and a hydrophobic monomer.
The polyvinyl resin in the present invention is a homopolymer or copolymer of an ethylenically unsaturated monomer, and examples thereof include acrylic resins and styrene resins.

The hydrophilic monomer is a monomer containing hydrophilicity that is an ionic group or a nonionic group. The ionic group may be a cation or an anion.
Both cationic groups and anionic groups provide amphoteric stabilization to the dispersant.
Preferred anionic groups are carboxyl groups, phenolic hydroxy groups, sulfonic acid groups, sulfuric acid groups, phosphonic acid groups, polyphosphoric acid groups, phosphoric acid groups, and salts thereof.
Preferred cationic groups are a quaternary ammonium group, a benzalkonium group, a guanidinium group, a biguanidinium group, and a pyridinium group. These may be in the form of salts such as hydroxides, sulfates, nitrates, chlorides, bromides, iodides and fluorides.
The nonionic group is preferably a glucooxide structure, a sugar structure, a pyrrolidone structure, an acrylamide group, a hydroxy group or a poly (alkylene oxide) group, and more preferably a poly (ethylene oxide) group or a poly (propylene oxide) group. _{preferably, - (CH 2 CH 2 O} ) n H or - it is more preferably an alkyl _{- (CH 2 CH 2 O)} n C 1-4. Here, n represents 3 to 200 (preferably 4 to 20). Further, hereinafter, for example, the expression of C _1-4- represents “having 1 to 4 carbon atoms”.
The polymer may contain only nonionic groups, a plurality of nonionic groups throughout the polymer, and one or more polymer chains containing nonionic groups. A hydroxy group is inserted using, for example, polyvinyl alcohol, a (meth) acryl compound having a hydroxy group, or cellulose. The ethyleneoxy group is inserted using a polymer chain such as polyethylene oxide.

A hydrophobic monomer is a monomer containing a hydrophobic group. Typical ones having a hydrophobic group are hydrocarbons, fluorocarbons, poly C _3-4 -alkyleneoxys and alkylsiloxanes having a hydrophilic group of 3 or less, preferably 0. Further, the hydrophobic monomer may have propylene oxide in a side chain or a straight chain.
The polymer may be a homopolymer, but is preferably a copolymer. The polymer may be a random polymer (statistically short blocks or segments) or a graft polymer (long blocks or segments). The polymer may also be an alternating polymer. The polymer may be branched but is preferably linear. The polymer may have more than one segment (eg, block and graft, copolymer), but is preferably random.
In embodiments where the polymer has two or more segments, it is preferred that at least one segment is hydrophobic and at least one segment is hydrophilic relative to each other. A preferred method for forming the hydrophobic and hydrophilic segments includes a method by copolymerization of hydrophobic and hydrophilic monomers, respectively. If the polymer has at least one hydrophobic segment and at least one hydrophilic segment, the carboxyl group may be in the hydrophobic segment, in the hydrophilic segment, or in both segments.

The vinyl polymer (polyvinyl resin) may be produced by any suitable means. A preferred method for producing a vinyl polymer is free radical polymerization using (meth) acrylate and a vinyl monomer such as vinyl naphthalene or styrene monomer. Suitable free radical polymerization is not limited to suspension polymerization, solution polymerization, dispersion polymerization and emulsion polymerization, but is preferably solution polymerization.
The vinyl polymer is preferably a (meth) acrylate monomer.
The vinyl polymer is preferably a copolymer.
Copolymers derived from hydrophobic and hydrophilic monomers are preferably substantially free of segments. For example, the copolymer is made by free radical polymerization such that the segment length is very short or absent. Such cases are often referred to as “random” polymerization. The copolymer having segments is produced by a polymerization method such as living polymerization, in particular group transfer polymerization, atom transfer polymerization, macromonomer polymerization, graft polymerization, anionic or cationic polymerization.
Suitable hydrophilic vinyl monomers are nonionic and ionic monomers.
Preferred nonionic monomers are saccharides, glucose compounds, amide compounds and pyrrolidone compounds, particularly those having a hydroxy group and an ethoxy group.
Examples of preferred nonionic monomers include hydroxyethyl acrylate, hydroxyethyl methacrylate, vinyl pyrrolidone, ethoxylated (meth) acrylate and (meth) acrylamide.
Suitable ionic vinyl monomers may be cationic.

Preferred anionic vinyl monomers include at least one selected from the group consisting of a carboxyl group, a phosphoric acid group, and a sulfonic acid group (these acids may be free or salts). Preferred examples include (meth) acrylic acid, styrene sulfonic acid, vinyl benzyl sulfonic acid, vinyl sulfonic acid, (meth) acryloyloxyalkyl sulfonic acid (for example, acryloyloxymethyl sulfonic acid, acryloyloxyethyl sulfonic acid, acryloyloxypropyl sulfone). Acid, acryloyloxybutylsulfonic acid, methacryloyloxymethylsulfonic acid, methacryloyloxyethylsulfonic acid, methacryloyloxypropylsulfonic acid, methacryloyloxybutylsulfonic acid), 2-acrylamide-2-alkylalkanesulfonic acid (for example, 2-acrylamide- 2-methylethanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylbutanesulfonic acid), -Methacrylamide-2-alkylalkanesulfonic acid (eg 2-methacrylamide-2-methylethanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, 2-methacrylamide-2-methylbutanesulfonic acid), Mono (acryloyloxyalkyl) phosphate (eg, mono (acryloyloxyethyl) phosphate, mono (3-acryloyloxypropyl) phosphate), mono (methacryloyloxyalkyl) phosphate (eg, mono (methacryloyloxyethyl) phosphate Salt, mono (3-methacryloyloxypropyl) phosphate).
Preferred cationic vinyl monomers are those containing quaternary ammonium groups, pyridinium groups, guanidinium groups or biguanidinium groups.
Preferred hydrophobic vinyl monomers do not have hydrophilic groups. Preferred hydrophobic vinyl monomers include C _1-20 -hydrocarbyl (meth) acrylate, butadiene, styrene and vinyl naphthalene, such as C _1-20 -hydrocarbyl (meth) acrylate (eg, methyl (meth) acrylate, butyl ( (Meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isobornyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate) Methyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, and phenoxyethyl methacrylate are particularly preferable. These hydrocarbyl groups may be branched but are preferably linear.

Polyesters having at least one carboxyl group are also produced by reaction of a diol monomer with an excess of dicarboxylic acid monomer. The carboxyl group can also be introduced by copolymerization of a diol having a carboxyl group and a dicarboxylic acid monomer.
Polyesters are typically made by esterification of a dicarboxylic acid and a diol.
A polyester having a carboxyl group can be produced, for example, by subjecting a carboxyl group-containing compound and a hydroxyl group-containing compound to a dehydration condensation reaction by a known method such as a melting method or a solvent method so that the carboxyl group remains. it can.
Examples of the polyester include those obtained by appropriately selecting and dehydrating and condensing a compound having a carboxyl group such as a monobasic acid and a polybasic acid and a compound having a hydroxyl group such as a diol and a polyol. Or the thing using fatty acids becomes alkyd resin.

The carboxyl group which the polyester used by this invention has is an unreacted carboxyl group mainly derived from the polybasic acid more than the dibasic acid which comprises polyester.
Examples of polybasic acids include adipic acid, (anhydrous) succinic acid, sebacic acid, dimer acid, (anhydrous) maleic acid, (anhydrous) phthalic acid, isophthalic acid, terephthalic acid, tetrahydro (anhydride) phthalic acid, hexahydro ( Anhydrous) phthalic acid, hexahydroterephthalic acid, 2,6-naphthalenedicarboxylic acid, (anhydrous) trimellitic acid, (anhydrous) pyromellitic acid and the like.

  Examples of compounds having a carboxyl group that can be used in addition to polybasic acids include lower alkyl esters of acids such as dimethyl terephthalate; monobasic acids such as benzoic acid, p-tertiarybutyl benzoic acid, rosin, and hydrogenated rosin. Acids; fatty acids and oils; macromonomers having one or two carboxyl groups at the molecular terminals; 5-sodium sulfoisophthalic acid and dimethyl esters thereof.

  Examples of the compound having a hydroxyl group include ethylene glycol, neopentyl glycol, propylene glycol, diethylene glycol, dipropylene glycol, 2-methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 1 , 4-butanediol, 1,3-propanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, 1,5-pentanediol, alkylene oxide adduct of bisphenol A, hydrogenated bisphenol A, hydrogenated Alkylene oxide adducts of bisphenol A, diols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol; glycerin, trimethylolpropane, trimethylolethane, diglycerin, pentaerythridine Polyols such as lithol and trishydroxyethyl isocyanurate; monoglycidyl compounds such as “Cardura E-10” (a glycidyl ester of a synthetic fatty acid manufactured by Shell Chemical Industry Co., Ltd.), a macro having two hydroxyl groups at one molecular end And monomers.

In addition, when synthesizing polyester, hydroxyl group-containing fatty acids or fats such as castor oil and 12-hydroxystearic acid; compounds having a carboxyl group and a hydroxyl group such as dimethylolpropionic acid, p-hydroxybenzoic acid and ε-caprolactone Can also be used.
Furthermore, a part of the dibasic acid can be replaced with a diisocyanate compound.
A polyester having a carboxyl group can also be produced by a method in which an anhydride such as maleic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride is added to a hydroxyl group-containing polyester. be able to.
A polyester having a hydroxyl group and a carboxyl group can be easily produced by, for example, reacting a hydroxyl group and a carboxyl group so as to remain in a dehydration condensation reaction of a polyester resin according to a known method.

  Polyester having a tertiary amino group and a carboxyl group is obtained by using a polyester resin, for example, a compound having a tertiary amino group and a hydroxyl group such as triethanolamine, N-methyldiethanolamine, N, N-dimethylethanolamine, etc. It can manufacture easily by using as an alcohol component at the time of manufacture.

Polyester having a radically polymerizable unsaturated group and a carboxyl group is, for example,
To a polyester having a hydroxyl group and a carboxyl group, a radical polymerizable unsaturated group-containing monomer having an isocyanate group such as 2-methacryloyloxyethyl isocyanate, or an acid anhydride having a radical polymerizable unsaturated group such as maleic anhydride. The addition reaction method,
A method of adding a polymerizable monomer having an epoxy group to a polyester resin having a carboxyl group;
A method of synthesizing a polyester resin using a radical polymerizable unsaturated group-containing monomer such as maleic anhydride as an acid component;
Etc. can be easily manufactured.

Polyurethane is preferably produced by a condensation reaction of a polyisocyanate component (for example, diisocyanate) and a polyol component (for example, diol).
Polyurethane having a carboxyl group can be easily obtained by reacting a polyisocyanate component with a polyol component containing a compound having a carboxyl group and a hydroxyl group such as dimethylolpropionic acid as a component for introducing a carboxyl group. Can be manufactured.
As the polyol component, in addition to the diol component listed in the polyester production method, a trifunctional or higher functional polyol compound may be used as necessary.
Examples of the polyisocyanate component include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, hexamethylene diisocyanate, phenylene diisocyanate, 1,5-naphthalene diisocyanate, and metaxylylene diisocyanate. In addition to diisocyanate compounds such as isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated 4,4′-diphenylmethane diisocyanate, hydrogenated metaxylylene diisocyanate, crude 4,4′-diphenylmethane diisocyanate, and polymethylene polyphenyl isocyanate Isocyanate compounds can also be used.

The polyurethane may be produced by a conventional method. For example, the addition reaction is preferably performed at room temperature or a temperature of about 40 to 100 ° C. in an inert organic solvent solution that does not react with an isocyanate group. At that time, a known catalyst such as dibutyltin dilaurate may be used.
A known chain extender such as diamine, polyamine, N-alkyl dialkanolamine such as N-methyldiethanolamine; dihydrazide compound can be used in the reaction system for producing polyurethane.

A polyurethane having a hydroxyl group and a carboxyl group can be easily produced, for example, by reacting at a ratio that the hydroxyl group is larger than the isocyanate group when producing the polyurethane. Alternatively, it can also be easily produced by subjecting a polyisocyanate having a carboxyl group and a terminal isocyanate group to an addition reaction with a compound having two or more hydroxyl groups in one molecule.
A polyurethane having a tertiary amino group and a carboxyl group can be easily produced, for example, by using an N-alkyl dialkanolamine such as N-methyldiethanolamine as a part of the polyol component.
A polyurethane having a blocked isocyanate group and a carboxyl group can be easily produced by, for example, adding a known blocking agent to a polyisocyanate having a carboxyl group and a terminal isocyanate group.
A polyurethane having an epoxy group and a carboxyl group can be easily produced by, for example, adding a compound having a hydroxyl group and an epoxy group to a polyisocyanate having a carboxyl group and a terminal isocyanate group.
Examples of the compound having a hydroxyl group and an epoxy group include glycidol, glycerin diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl ether of bisphenol A, and the like.

  A polyurethane having a radically polymerizable unsaturated group and a carboxyl group as an acidic group is, for example, a polyisocyanate having a terminal isocyanate group, a polymerizable monomer having a hydroxyl group as described above, glycerol mono (meth) acrylate, and trimethylol. It can be easily produced by a method in which a compound having a hydroxyl group and a radically polymerizable unsaturated group such as propanedi (meth) acrylate or pentaerythritol triacrylate is subjected to an addition reaction.

  A polyurethane having a hydrolyzable alkoxysilane group and a carboxyl group as an acidic group is, for example, a polyisocyanate having a terminal isocyanate group, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-aminopropyltrimethyl. It can be easily produced by a method in which a silane coupling agent having an active hydrogen capable of reacting with an isocyanate group such as methoxysilane or γ-aminopropyltriethoxysilane is subjected to an addition reaction.

  The polymer is selected to match the dispersion medium used and to match the liquid color developer (vehicle) in the final composition used (eg, ink composition). For example, when the aqueous pigment dispersion is used in an aqueous inkjet recording ink composition, the polymer is preferably hydrophilic.

  Commercially available dispersants can be used as long as they can be used in an aqueous system and are not significantly colored. , SOLPERSE41090, SOLPERSE43000, SOLPERSE44000, SOLPERSE54000; DISPERBYK-180 series, DISPERBYK-181, DISPERBYK-182, DISPERBYK-183, DISPERBYK-183, DISPERBYK-183, DISPERBYK-183, 84 DISPERBYK 190, DISPERBYK-191, DISPERBYK-192, DISPERBYK-193, DISPERBYK-194, DISPERBYK-2010, DISPERBYK-2012, DISPERBYK-2013, DISPERBYK-2015, DISPERBYK-2055, DISPERBYSP-20K, SPPERBYSP-20K DISPERBYK-2091, DISPERBYK-2095, DISPERBYK-2096; EFKA (registered trademark) series EFKA 4500, EFKA 4510, EFKA 4520, EFKA 4550, EFKA 4560, EFKA 4570, EFKA 4570, EFKA 4570, EFKA 4570, EFKA 4570 E KA 4800, EFKA 5071, EFKA 6220, EFKA 6225, EFKA 6230, Dispex can be used (TM) Ultra PX 4575, and the like.

In the aqueous pigment dispersion of the present invention, the content of the azo pigment represented by formula 1 is P, the content of the first dispersant is D ¹ , and the ratio (mass ratio) of the content D ¹ to the content P ) a when a D ¹ / P value, D ¹ / P value thereof is preferably 0.05 to 1.2, more preferably 0.1 to 0.8, 0. More preferably, it is 2 or more and 0.75 or less, and particularly preferably 0.3 or more and 0.7 or less. Within the above range, the storage stability is more excellent.
The content of the azo pigment represented by Formula 1 of the aqueous pigment dispersion of the present invention is P, and the content of the second dispersion agent D ^2, the ratio of the content P and the content D ² (mass ratio ) a when a D ² / P value, D ² / P value thereof is preferably 0.05 to 1.2, more preferably 0.1 to 0.8, 0. More preferably, it is 2 or more and 0.75 or less, and particularly preferably 0.3 or more and 0.7 or less. Within the above range, the storage stability is more excellent.
Further, the content of D ¹ of the first dispersant in the aqueous pigment dispersion of the present invention, the mass ratio of the content of D ² of the second ^{dispersant, D 1: D 2 = 5} : 1~1 : 5, preferably 3: 1 to 1: 3, and more preferably 1: 2 to 2: 1. Within the above range, the storage stability is more excellent.
Further, the total content of the first dispersant and the second dispersant in the aqueous pigment dispersion of the present invention is 10 to 80 parts by mass with respect to 100 parts by mass of the azo pigment represented by Formula 1. It is preferably 20 to 75 parts by mass, and more preferably 30 to 70 parts by mass.

The aqueous pigment dispersion of the present invention may contain a dispersant other than the first dispersant and the second dispersant.
When the other dispersant is contained, the other dispersant is a dispersant having an amine value of 5 mgKOH / g or more and an amine value> acid value, or a long-chain fatty acid salt or an acid value of 5 mgKOH / g. It is preferable that the dispersant has an acid value ≧ an amine value. When the other dispersant is not the above-described dispersant, the total content of the first dispersant and the second dispersant may be 50% by mass or more based on the total mass of the dispersant in the aqueous pigment dispersion. Preferably, it is 70 mass% or more, and it is still more preferable that it is 90 mass% or more.

<Water>
The aqueous pigment dispersion of the present invention contains water as a dispersion medium.
The water may be tap water or well water, and is not particularly limited. For example, pure water or ultrapure water such as ion exchange water, ultrafiltration water, reverse osmosis water, or distilled water is preferable. Furthermore, it is also preferable to use water sterilized by ultraviolet treatment, hydrogen peroxide treatment or the like for the purpose of preventing the generation of molds and bacteria.

In the present invention, the aqueous pigment dispersion may contain an organic solvent in addition to the above water. In addition, it is preferable that the amount of the organic solvent contained is less than the content of water, and the content of the organic solvent is less than 100 parts by mass with respect to 100 parts by mass of water contained in the aqueous pigment dispersion. Preferably, it is 50 parts by mass or less, more preferably 30 parts by mass or less, and particularly preferably 10 parts by mass or less.
The organic solvent used in combination is preferably a water-soluble organic solvent, such as ethanol, methanol, butanol, propanol, isopropanol and other C1-C4 alkyl alcohols, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol. Monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, Ethylene glycol mono-t-butyl ether, diethylene glycol mono- -Glycol ethers such as butyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, dipropylene glycol mono-iso-propyl ether, 2-pyrrolidone , Formamide, acetamide, dimethyl sulfoxide, sorbit, sorbitan, acetin, diacetin, triacetin, sulfolane and the like. These may be used alone or in combination of two or more.

<Other ingredients>
The aqueous pigment dispersion of the present invention may contain other components in addition to the azo pigment represented by Formula 1, the first dispersant, the second dispersant, and water.
Examples of other components include preservatives and polyvalent ions.

-Preservative-
The preservative will be described. In the present invention, the preservative means a substance having a function of preventing the generation and growth of microorganisms, particularly bacteria and fungi.
Various preservatives that can be used in the present invention can be used.
Examples of the preservative include inorganic preservatives (such as silver ion-containing substances) and salts containing heavy metal ions. Organic preservatives include quaternary ammonium salts (tetrabutylammonium chloride, cetylpyridinium chloride, benzyltrimethylammonium chloride, etc.), phenol derivatives (phenol, cresol, butylphenol, xylenol, bisphenol, etc.), phenoxyether derivatives (phenoxyethanol) Etc.), heterocyclic compounds (benzotriazole, proxel, 1,2-benzisothiazolin-3-one, etc.), acid amides, carbamic acid, carbamates, amidine / guanidine, pyridines (sodium pyridinethione- 1-oxide, etc.), diazines, triazines, pyrrole / imidazoles, oxazoles / oxazines, thiazoles / thiadiazines, thioureas, thiosemicarbazides , Dithiocarbamates, sulfides, sulfoxides, sulfones, sulfamides, antibiotics (penicillin, tetracycline, etc.), sodium dehydroacetate, sodium benzoate, ethyl p-hydroxybenzoate, and salts thereof Things can be used.
In addition, as the antiseptic, those described in the antibacterial / antifungal handbook (Gihodo Publishing Co., Ltd .: 1986), the antibacterial / antifungal encyclopedia (edited by the Japanese Society for Antibacterial and Fungal Sciences) Can do.

As these compounds, various compounds such as oil-soluble structures and water-soluble structures can be used, but water-soluble compounds are preferred.
As the preservative, a phenol derivative or a heterocyclic compound is preferable, and a heterocyclic compound is more preferable.
The heterocyclic compound is preferably a thiazole compound or a benzotriazole compound. Among the antiseptics, thiazole compounds particularly function as antifungal agents. Examples of thiazole compounds include benzisothiazoline, isothiazoline, 1,2-benzisothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, 2- (thiocyanomethylthio) benzthiazole, 2- Examples include mercaptobenzthiazole and 3-allyloxy-1,2-benzisothiazole-1,1-oxide. Moreover, as a thiazole type antifungal agent, Proxel (trademark) series (BDN, BD20, GXL, LV, XL2, Ultra10, etc.) manufactured and sold by Arch Chemicals can also be used.

  The benzotriazole-based compound functions particularly as a rust preventive among antiseptics, and for example, when a metal material constituting an inkjet head (especially 42 alloy (a nickel-iron alloy containing 42% nickel)) is used as an ink. It is possible to prevent the generation of rust caused by contact with the rust. Examples of the benzotriazole compounds include 1H-benzotriazole, 4-methyl-1H-benzotriazole, 5-methyl-1H-benzotriazole, and sodium salts or potassium salts thereof.

One or more preservatives can be added to the aqueous solution in combination.
The preservative is preferably at least one selected from the group consisting of heterocyclic compounds, phenol derivatives, phenoxy ether derivatives, and alkanediols, and at least one preservative is a heterocyclic compound. Is more preferable.
More preferably, the preservative is a heterocyclic compound, and the heterocyclic compound is a thiazole compound or a benzotriazole compound.

  The content of the preservative in the aqueous pigment dispersion can be used in a wide range, but is preferably 0.01 to 20% by mass, preferably 0.1 to 10% by mass with respect to the azo pigment represented by Formula 1. % Is more preferable, and 0.5-5 mass% is still more preferable. By setting the content of the preservative within the above range, there is an effect of suppressing the growth of bacteria in the aqueous solution.

-Multivalent metal ion-
The aqueous pigment dispersion of the present invention may contain a polyvalent metal ion.
Examples of the polyvalent metal ion in the present invention include Fe ³⁺ , Fe ²⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Cd ²⁺ , Ni ²⁺ , Zn ²⁺ and Cu. ²⁺ , Co ²⁺ , Pb ²⁺ , Mn ²⁺ , Al ³⁺ , Cr ³⁺ , Sn ^{4+ and the} like.
The content of polyvalent metal ions in the aqueous pigment dispersion is preferably 10 ppm or less, more preferably 0.001 to 5 ppm. By setting the content of polyvalent metal ions in the aqueous pigment dispersion to the amount specified above, the pigment and / or dispersant in the aqueous pigment dispersion of the present invention suppresses the increase of coarse particles due to aggregation. can do.

<Method for producing aqueous pigment dispersion of the present invention>
The method for producing an aqueous pigment dispersion of the present invention comprises the steps a, in which an azo pigment represented by formula 1 or a tautomer thereof, and a first dispersant are dispersed in water to obtain an aqueous pigment dispersion A. Step b in which the azo pigment represented by Formula 1 or a tautomer thereof and the second dispersant are dispersed in water to obtain an aqueous pigment dispersion B, and the aqueous pigment dispersion A and the aqueous pigment dispersion And c) to obtain an aqueous pigment dispersion by mixing with B.
In the method for producing an aqueous pigment dispersion of the present invention, an aqueous pigment dispersion A containing a first dispersant and an aqueous pigment dispersion B containing a second dispersion are respectively prepared first, and then By mixing the aqueous pigment dispersion A and the aqueous pigment dispersion B to obtain an aqueous pigment dispersion, an aqueous pigment dispersion having excellent storage stability can be easily obtained. Although the detailed reason is unknown, it becomes difficult to desorb the pigment particles from the dispersant by the dispersant having a high adsorptivity to the pigment particles, particularly because the pigment dispersion is a combination of a plurality of specific dispersants. Further, it is presumed that the pigment particles can be stabilized without settling by the action of another dispersant at the same time.

-Step a-
The method for producing an aqueous pigment dispersion of the present invention comprises a step a in which an azo pigment represented by the formula 1 or a tautomer thereof, and a first dispersant are dispersed in water to obtain an aqueous pigment dispersion A. Including.
The preferred embodiment of the azo pigment represented by Formula 1 in Step a or a tautomer thereof and the first dispersant is the azo pigment represented by Formula 1 described above in the aqueous pigment dispersion of the present invention or the method thereof. This is the same as the preferred embodiment of the tautomer and the first dispersant.
In the aqueous pigment dispersion A obtained in step a, the content P ^a of the azo pigments represented by Formula 1, the content of the first dispersant and D ^1a, the content D ^1a content and P ^a the ratio (mass ratio) is taken as D ^1a / P ^a values, D ^1a / P ^a value thereof is preferably 0.1 to 1.0, is 0.2 to 0.9 More preferably, it is 0.3 or more and 0.8 or less. Within the above range, the dispersibility is excellent.
The total content of the azo pigment represented by Formula 1 and the tautomer thereof in the aqueous pigment dispersion A is preferably 0.1 to 30% by mass with respect to the total mass of the aqueous pigment dispersion A. More preferably, it is 0.5-25 mass%, It is still more preferable that it is 1-20 mass%, It is especially preferable that it is 3-15 mass%.

The dispersion method in the step a can be performed using a known method or a dispersion apparatus, and is not particularly limited. Step a includes, for example, a mill method (for example, colloid mill, ball mill, sand mill, bead mill, attritor, roll mill, jet mill, paint shaker, agitator mill, etc.), ultrasonic method (ultrasonic homogenizer), high-pressure emulsification dispersion method. (High-pressure homogenizer; specific commercially available devices such as gorin homogenizers, microfluidizers, DeBEE2000, etc.), high-speed stirring type dispersers, and the like can be used.
Among these, a mill system is preferable, a medium dispersion system (colloid mill, ball mill, sand mill, bead mill, etc.) is more preferable, and a bead mill is still more preferable.

In step a, the mixing and / or dispersion order of the azo pigment represented by the formula 1, the first dispersant and water is not particularly limited, and the dispersion may be prepared by mixing and dispersing in any order. Preferably, the specific pigment, the first dispersant, and water are mixed in advance to prepare a mixed solution, and this mixed solution is dispersed with a disperser to obtain the aqueous pigment dispersion A.
Further, the dispersion temperature and mixing dispersion time in step a are not particularly limited, and may be appropriately selected according to a desired dispersion state.
In step a, the dispersion is preferably performed so that the volume average particle size of the azo pigment represented by Formula 1 is in a desired range, and the volume average particle size of the azo pigment represented by Formula 1 is 100 nm or less. Thus, it is more preferable to disperse.
In step a, other components such as preservatives and polyvalent metal ions may be added as necessary.

-Step b-
The method for producing an aqueous pigment dispersion of the present invention comprises the step b of obtaining an aqueous pigment dispersion B by dispersing the azo pigment represented by formula 1 or a tautomer thereof and a second dispersant in water. Including.
A preferred embodiment of the azo pigment represented by the formula 1 in step b or its tautomer and the second dispersant is the azo pigment represented by the formula 1 described above in the aqueous pigment dispersion of the present invention or its This is the same as the preferred embodiment of the tautomer and the second dispersant.
In the aqueous pigment dispersion B obtained in step b, the content of the azo pigment represented by Formula 1 is P ^b , the content of the second dispersant is D ^1b , and the content D ^1b and the content P ^b are When the ratio (mass ratio) is D ^1b / P ^b value, the D ^1b / P ^b value is preferably 0.1 or more and 1.0 or less, and 0.2 or more and 0.9 or less. More preferably, it is 0.3 or more and 0.8 or less. Within the above range, the dispersibility is excellent.
The total content of the azo pigment represented by Formula 1 and the tautomer thereof in the aqueous pigment dispersion B is preferably 0.1 to 30% by mass with respect to the total mass of the aqueous pigment dispersion B. More preferably, it is 0.5-25 mass%, It is still more preferable that it is 1-20 mass%, It is especially preferable that it is 3-15 mass%.

The dispersion method in step b can be performed using a known method or a dispersion apparatus, and is not particularly limited. Moreover, the preferable aspect of the dispersion method in the process b is the same as the preferable aspect of the dispersion method in the process a mentioned above.
In step b, the mixing and / or dispersion order of the azo pigment represented by the formula 1, the second dispersant and water is not particularly limited, and the dispersion may be prepared by mixing and dispersing in any order. Preferably, the specific pigment, the second dispersant, and water are mixed in advance to prepare a mixed liquid, and this mixed liquid is dispersed with a disperser to obtain the aqueous pigment dispersion B.
Moreover, the dispersion temperature and mixing dispersion time in the step b are not particularly limited, and may be appropriately selected according to a desired dispersion state.
In step b, the dispersion is preferably performed so that the volume average particle diameter of the azo pigment represented by Formula 1 is in a desired range, and the volume average particle diameter of the azo pigment represented by Formula 1 is 100 nm or less. Thus, it is more preferable to disperse.
In step b, other components such as preservatives and polyvalent metal ions may be added as necessary.

-Process c-
The method for producing an aqueous pigment dispersion of the present invention includes a step c in which the aqueous pigment dispersion A and the aqueous pigment dispersion B are mixed to obtain an aqueous pigment dispersion.
In step c, the aqueous pigment dispersion A may be added to the aqueous pigment dispersion B and mixed, the aqueous pigment dispersion B may be added to the aqueous pigment dispersion A and mixed, or the aqueous pigment dispersion A may be mixed. The pigment dispersion A and the aqueous pigment dispersion B may be simultaneously added and mixed.
The mixing ratio (mass ratio) of the aqueous pigment dispersion A and the aqueous pigment dispersion B in step c is preferably aqueous pigment dispersion A: aqueous pigment dispersion B = 4: 1 to 1: 4. Is more preferably 1: 1 to 1: 3, and even more preferably 2: 1 to 1: 2. Within the above range, the dispersibility is excellent and the storage stability is excellent.

Step c is preferably a step of mixing the aqueous pigment dispersion A, the aqueous pigment dispersion B and water to obtain an aqueous pigment dispersion from the viewpoint of dispersion stability, ease of mixing, and ease of concentration adjustment. .
There is no restriction | limiting in particular in the addition amount of the water in process c, It can add suitably so that it may become a desired pigment density | concentration.
The mixing method in step c is not particularly limited, and a known mixing method and a known mixing apparatus can be used, but it is preferable to mix by stirring and mixing.
Further, the mixing temperature and mixing time in step c are not particularly limited, and may be appropriately selected according to the desired progress of mixing.
Preferred inclusion of the azo pigment represented by Formula 1 and its tautomer, first dispersant, second dispersant and water in the aqueous pigment dispersion produced by the method for producing an aqueous pigment dispersion of the present invention The amount is the same as the preferred content in the aqueous pigment dispersion of the present invention described above.
In step c, other components such as preservatives and polyvalent metal ions may be added as necessary.

Furthermore, in step c, one or more of the aqueous pigment dispersion C containing the azo pigment represented by Formula 1 or a tautomer thereof, a third dispersant, and water may be further mixed. The third dispersant is preferably a dispersant having an amine value of 10 mgKOH / g or more, or a long-chain fatty acid salt, or a dispersant having an acid value of 5 mgKOH / g or more.
As a preparation method of the aqueous pigment dispersion C, it is preferable to prepare it by the same method as the aqueous pigment dispersion A or B.

-Process d: Heat treatment process-
The method for producing an aqueous pigment dispersion of the present invention preferably includes a step of heat-treating the aqueous pigment dispersion obtained in step c (hereinafter also simply referred to as “heat-treatment step”). By having the heat treatment step, the relationship between the pigment and the dispersant in the aqueous pigment dispersion becomes more stable, and an aqueous pigment dispersion excellent in storage stability can be obtained.
The heating temperature in the heat treatment step is preferably 40 ° C. or higher and 100 ° C. or lower, more preferably 50 ° C. or higher and 85 ° C. or lower, and still more preferably 60 ° C. or higher and 80 ° C. or lower.
The heating time in the heat treatment step is preferably 5 minutes or longer, more preferably 5 minutes to 24 hours, and further preferably 30 minutes to 12 hours.
In the heat treatment step, the heat treatment may be performed while stirring.

  The method for producing an aqueous pigment dispersion of the present invention may include other steps in addition to the above steps a to d.

-PH adjustment step-
The method for producing an aqueous pigment dispersion of the present invention may include a pH adjusting step for adjusting the pH of the aqueous pigment dispersion. By adjusting the pH to a specific value, an aqueous pigment dispersion excellent in storage stability can be obtained.
The pH adjustment step may be performed at a desired timing as long as it is after step a and step b, but is preferably performed between step c and step d or after step d, and is performed after step d. Is more preferable.
In addition, the method for producing the aqueous pigment dispersion of the present invention is performed in the order of step c, deionization step described later, pH adjustment step, and step d, or step c, step d, deionization step described later. It is preferable to carry out in the order of the pH adjustment step, and it is particularly preferred to carry out in the order of the step c, the step d, the deionization step described later, and the pH adjustment step.
The pH adjuster is not particularly limited as long as it can adjust the pH to a desired value without adversely affecting the recording ink to be prepared, and can be appropriately selected according to the purpose. Amines (eg, diethanolamine, triethanolamine, triisopropanolamine, 2-amino-2-ethyl-1,3-propanediol), alkali metal hydroxides (eg, lithium hydroxide, sodium hydroxide, hydroxide) Potassium), ammonium hydroxide (for example, ammonium hydroxide, quaternary ammonium hydroxide), phosphonium hydroxide, alkali metal carbonate, and the like.
The pH of the aqueous pigment dispersion is preferably 6 to 11 and particularly preferably 7 to 10 from the viewpoint of storage stability.

-Sterilization process-
The sterilization referred to in the present invention means an operation having a sterilizing action, and examples thereof include addition of an additive having a sterilizing effect such as irradiation with light such as ultraviolet rays (UV) and alcohol. Among them. Light irradiation is preferred.
By having a sterilization step, an aqueous pigment dispersion superior in storage stability can be obtained.
As the light irradiation means, those capable of irradiating near-ultraviolet light to ultraviolet light of 400 nm or less are preferable, and specifically, a xenon lamp, a high-pressure mercury lamp, a black light, a sterilizing lamp, or the like is preferably used.
The light irradiation time and the light irradiation amount are not particularly limited and can be appropriately selected.

-Deionization process-
The method for producing an aqueous pigment dispersion of the present invention may include a deionization step for removing at least part of the ionic component. By removing ionic components contained as impurities in the specific pigment or dispersant, an aqueous pigment dispersion having excellent storage stability can be obtained.
The deionization step may be performed at a desired timing, but is preferably performed between step c and step d or after step d, and more preferably after step d.
Examples of the method for removing the ionic component include a method using a membrane separation method such as ultrafiltration and nanofiltration, a method of adding an ion exchange resin, and the like.

-Centrifugation process-
The method for producing an aqueous pigment dispersion of the present invention may include a step of centrifuging the aqueous pigment dispersion obtained in step c. Coarse particles can be removed by centrifugation. In addition, the method for producing an aqueous pigment dispersion of the present invention may include a step of centrifuging the aqueous pigment dispersion A before the step c, and the aqueous pigment dispersion B is added before the step c. A step of centrifuging may be included.
The centrifugal separation step is preferably performed before the filtration step described later. By having the centrifugal separation step before the filtration step, it is possible to suppress the coarse particles from being clogged and reducing the filterability.
As centrifugal force at the time of centrifugal separation, 500G to 50,000G is preferable, 700G to 20,000G is more preferable, and 1,000G to 15,000G is still more preferable. When it is 500 G or more, coarse particles can be sufficiently settled and removed, and when it is 50,000 G or less, sedimentation of the dispersed pigment is suppressed.

-Filtration process-
The method for producing an aqueous pigment dispersion of the present invention may include a step of filtering the aqueous pigment dispersion obtained in step c. In addition, the method for producing an aqueous pigment dispersion of the present invention may include a step of filtering the aqueous pigment dispersion A before the step c, and the aqueous pigment dispersion B is filtered before the step c. The process of carrying out may be included.
Coarse particles can be removed by filtration. The filtration step is not particularly limited as long as it is after the pigment is dispersed, but is preferably performed after the addition of the preservative or as the final step of completing the aqueous pigment dispersion.
In particular, in the case of having the heat treatment step, a part of the dispersed pigment and dispersant may be dried or aged to become coarse particles and settle.
The filter that can be used is not particularly limited as long as filtration can be performed, but filter cloth, filter paper, and membrane are preferable. The pore size of the filter is preferably 0.1 mm or less, more preferably 10 μm or less, still more preferably 5 μm or less, and particularly preferably 1 μm or less.

(Coloring composition)
The colored composition of the present invention is a colored composition using the aqueous pigment dispersant of the present invention as a raw material, and preferably contains the aqueous pigment dispersion of the present invention.
The coloring composition of the present invention may contain other additives as necessary within a range that does not impair the effects of the present invention. Other additives include, for example, anti-drying agents (wetting agents), anti-fading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, anti-mold agents, pH adjusters, surface tension adjusters, antifoaming agents, Known additives (described in JP-A No. 2003-306623) such as a viscosity modifier, a dispersant, a dispersion stabilizer, a rust inhibitor, and a chelating agent can be used. These various additives are directly added to the ink liquid in the case of water-soluble ink.

  Examples of the coloring composition using the aqueous pigment dispersion obtained in the present invention include water-based paints such as automobiles, coated steel plates, building materials, and cans, printing agents for dyeing fibers, water-based inks such as gravure inks and flexographic inks, Water-based ballpoint pens, fountain pens, water-based sign pens, inks for writing instruments such as water-based markers, water-based recording liquids for on-demand type ink jet printers such as bubble jet (registered trademark), thermal jet, and piezo methods Examples of color filter dispersions used in personal computers are not limited to these applications.

  The colored composition includes an aqueous pigment dispersion obtained by the present invention, a film-forming resin, its curing agent, various auxiliary agents, an organic solvent, water, a basic substance, various pigments, and the like depending on its use. It is prepared by appropriately selecting and mixing.

  The content ratio of the aqueous pigment dispersion obtained by the present invention in the coloring composition is preferably 50% by mass or less, particularly preferably in the range of 0.1 to 40% by mass in terms of pigment. When the ratio of the pigment exceeds 50% by mass, the viscosity in the colored composition tends to be high, and the object to be coated tends not to be colored.

  Examples of the film-forming resin include natural proteins such as glue, gelatin, casein, albumin, gum arabic, and fish mulberry, alginic acid, methylcellulose, carboxymethylcellulose, polyethylene oxide, hydroxyethylcellulose, polyvinyl alcohol, polyacrylamide, and aromatic amide. , Synthetic polymers such as polyacrylic acid, polyvinyl ether, polyvinyl pyrrolidone, acrylic resin, polyester, alkyd resin, urethane resin, amide resin, melamine resin, ether resin, fluorine resin, styrene acrylic resin, styrene maleic acid resin, photosensitivity Common materials such as a resin, a thermosetting resin, an ultraviolet curable resin, and an electron beam curable resin are exemplified, but the invention is not particularly limited thereto. These are selected and used depending on the use of the coloring composition.

  The ratio of these coating film-forming resins in the colored composition is preferably in the range of 0 to 50% by mass. Depending on the application, the resin component in the dispersant used in the aqueous pigment dispersion acts as a resin for forming a coating film, or an application that does not require a resin for coating, such as a recording liquid The coating composition-forming resin is not necessarily required in the coloring composition.

  Examples of the curing agent for the film-forming resin include amino resins such as melamine resin, benzoguanamine resin and urea resin, phenol resins such as trimethylolphenol and its condensate, tetramethylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI). , Hexamethylene diisocyanate (HDI), naphthalene diisocyanate (NDI), isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), polyisocyanates such as modified isocyanates and blocked isocyanates, aliphatic amines, aromatic amines, N- Amines such as methylpiperazine, triethanolamine, morpholine, dialkylaminoethanol, benzyldimethylamine, polycarboxylic acid, phthalic anhydride, maleic anhydride Of acid, hexahydrophthalic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol bis trimellitate, bisphenol A type epoxy resin, phenolic epoxy resin, glycidyl methacrylate copolymer, carboxylic acid Glycidyl ester resins, epoxy compounds such as alicyclic epoxies, polyether polyols, polybutadiene glycols, polycaprolactone polyols, alcohols such as trishydroxyethyl isocyanate (THEIC), peroxide radical curing, UV curing and electron beam curing. Examples thereof include polyvinyl compounds, polyallyl compounds as saturated group-containing compounds, vinyl compounds such as a reaction product of glycol or polyol and acrylic acid or methacrylic acid.

  Although a hardening | curing agent is suitably selected and used by a use or aptitude, it may not be used. The use ratio of the curing agent is preferably in the range of 0 to 50% by mass and particularly preferably in the range of 0 to 40% by mass with respect to 100% by mass of the film-forming resin.

  Examples of the organic solvent include alcohols such as methyl alcohol, ethyl alcohol, n-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, n-propyl alcohol, and isopropyl alcohol; amides such as dimethylformaldehyde and dimethylacetamide; acetone, Ketones such as methyl ethyl ketone; Ethers such as tetrahydrofuran, dioxane, ethylene glycol methyl ether, ethylene glycol ethyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether; ethylene glycol, propylene glycol , Butylene glycol, triethylene glycol, 1,2,6 Hexane triol, thiodiglycol, diethylene glycol, polyethylene glycol, polypropylene glycol, polyhydric alcohols such as glycerin; N- methyl - pyrrolidone, 1,3-dimethyl-2-imidazolidinone. Of these water-soluble organic solvents, polyhydric alcohols and ethers are preferred.

  The content ratio of the organic solvent in the aqueous coloring liquid is preferably 50% by mass or less, and particularly preferably in the range of 0 to 30% by mass. Needless to say, it is preferable that the aqueous coloring liquid is not inferior in terms of environmental problems unless the performance of the aqueous coloring liquid is inferior.

Auxiliaries used as necessary include dispersion wetting agents, anti-skinning agents, UV absorbers, antioxidants, preservatives, fungicides, pH adjusters, viscosity adjusters, chelating agents, surfactants And various auxiliary materials and stabilizers such as, but not limited to.
Examples of basic substances include inorganic compounds such as sodium hydroxide and potassium hydroxide; ethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N-ethyldiethanolamine, 2-amino-2-methylpropanol, 2 Examples include, but are not limited to, organic amine compounds such as ethyl-2-amino-1,3-propanediol, 2- (aminoethyl) ethanolamine, tris (hydroxymethyl) aminomethane, ammonia, piperidine and morpholine. Is not to be done.

  As a disperser for dispersing the aqueous pigment dispersion of the present invention in these colored compositions, a simple known disperser such as a disper is sufficient, but is not limited thereto.

  As a method for producing a colored composition, the aqueous pigment dispersion of the present invention and a film-forming resin, a curing agent, various auxiliary agents, an organic solvent, water, various pigment compositions, etc. are simply added and mixed. In the case of adding a high-viscosity resin or organic solvent, there is a method in which the aqueous pigment dispersion of the present invention is stirred and the resin, curing agent, organic solvent, and various auxiliaries are sequentially added therein. More preferred.

  Moreover, the coloring composition containing the aqueous pigment dispersion liquid obtained by this invention can be manufactured according to the use. Furthermore, storage stability, solvent stability required for coloring compositions, performance such as hydrophilicity to prevent clogging of nozzles at pen tips such as writing instruments, water resistance, weather resistance, transparency, sharpness, etc. It is possible to provide a coating film excellent in various aptitudes.

(Ink composition)
The ink composition of the present invention is an ink composition using the aqueous pigment dispersant of the present invention as a raw material, and preferably contains the aqueous pigment dispersion of the present invention.
It does not specifically limit as an ink composition, What is necessary is just to use the coloring composition mentioned above for an ink use suitably. Specifically, water-based inks such as gravure inks and flexo inks, water-based ballpoint pens, fountain pens, water-based sign pens, inks for writing tools such as water-based markers, bubble-jet (registered trademark) methods, thermal jet methods, piezo methods, and other on-demand types It can be used as ink for inkjet printers.
Among these, the ink composition of the present invention is suitable as an ink composition for inkjet recording.

  In the ink composition for ink jet recording to which the aqueous pigment dispersion of the present invention is applied, the average particle diameter (Mv) of the pigment is preferably in the range of 20 to 250 nm, and more preferably in the range of 20 to 100 nm. . If the average particle diameter of the pigment is 20 nm or more, the dispersion stability is improved, so that good storage stability and ejection stability can be obtained, and a high OD value of the recorded matter can be secured. Moreover, if the average particle diameter of a pigment is 250 nm or less, nozzle clogging can be prevented and sedimentation of a resin adsorbing the pigment can also be suppressed.

  The ink composition for ink jet recording is produced using the aqueous pigment dispersion of the present invention, and the pigment content relative to the total amount of the ink composition is preferably in the range of 2 to 15% by mass. If the pigment content is 2% by mass or more, a high OD value of the recorded matter can be secured. In addition, when the pigment content is 15% by mass or less, it is easy to match the ink jet proper physical property value, and it is possible to secure better storage stability and ejection stability.

Moreover, the ink composition for inkjet recording can also use an organic solvent together with water as a solvent. Such an organic solvent has compatibility with water, improves the permeability of the ink composition into the recording medium and prevents nozzle clogging, and dissolves components in the ink composition such as a penetrant described later. What improves the property is preferable.
For example, C1-C4 alkyl alcohols such as ethanol, methanol, butanol, propanol, isopropanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol Monoethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-t-butyl ether 1-methyl-1-methoxybuta , Glycol ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, dipropylene glycol mono-iso-propyl ether, 2-pyrrolidone, formamide, acetamide, dimethyl sulfoxide, sorbit Sorbitan, acetin, diacetin, triacetin, sulfolane and the like. One or more of these solvents can be used in the ink composition of the present invention, preferably at 0 to 10% by mass.

The ink composition for inkjet recording preferably contains a surfactant from the viewpoint of improving the printing quality.
The surfactant can be selected from commonly used anionic surfactants, cationic surfactants, amphoteric surfactants and nonionic surfactants, and among these, nonionic surfactants are particularly preferred.
Specific examples of nonionic surfactants include acetylene glycol surfactants, acetylene alcohol surfactants, polyoxyethylene alkyl ethers, polyoxyethylene phenyl ethers, and the like. An ink composition with less foaming compared to the surfactant can be obtained. Furthermore, among nonionic surfactants, acetylene glycol surfactants are particularly preferred when used in ink jet recording because an ink composition with little foaming can be obtained.
Examples of such acetylene glycol surfactants include 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 3,6-dimethyl-4-octyne-3,6-diol. 3,5-dimethyl-1-hexyn-3-ol, or substances obtained by adding an average of 1 to 30 ethyleneoxy groups or propyleneoxy groups to each of a plurality of hydroxyl groups in each of these substances.
Moreover, as an acetylene glycol type surfactant, a commercial item can also be used, for example, "Orphine E1010" and "Orphine STG" (above, Nissin Chemical Industry Co., Ltd. product) etc. are mentioned. These 1 type (s) or 2 or more types can be used.
The content of the acetylene glycol surfactant is preferably 0.1 to 3% by mass, more preferably 0.5 to 1.5% by mass in the ink composition of the present invention.

The ink composition for ink jet recording preferably contains a penetrating agent in order to further improve the fixing property to the recording medium and to improve the abrasion resistance of the recorded image.
Such penetrants include glycols such as diethylene glycol mono-n-butyl ether, diethylene glycol mono-t-butyl ether, triethylene glycol mono-n-butyl ether, propylene glycol mono-n-butyl ether, and dipropylene glycol mono-n-butyl ether. Ethers are preferred, and diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether, and dipropylene glycol mono-n-butyl ether are particularly preferred from the viewpoints of excellent penetrating performance and easy handling.
The content of the penetrant is 1 to 20% by mass in the ink composition of the present invention in terms of improving the penetrability and quick-drying property of the ink composition and effectively preventing the occurrence of ink bleeding. Preferably, it is 2-10 mass%.

The ink composition for ink-jet recording preferably contains water-soluble glycols in order to prevent nozzle clogging and improve reliability.
Examples of such water-soluble glycols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol having a molecular weight of 2,000 or less, 1,3- Dihydric alcohols such as propylene glycol, isobutylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, glycerin, Examples thereof include trivalent or higher alcohols such as mesoerythritol and pentaerythritol.
1 type (s) or 2 or more types can be used for water-soluble glycols.
The content of the water-soluble glycol is preferably 1 to 30% by mass in the ink composition of the present invention.

Further, in the ink composition for ink jet recording, like the water-soluble glycols, an antifungal agent or an antiseptic can be contained in order to prevent clogging of the nozzle.
For example, sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-dibenzisothiazolin-3-one (AVECIA Proxel CRL, Proxel BDN) , Proxel GXL, Proxel XL-2, Proxel TN) and the like.
One or more of these antifungal agents and preservatives can be preferably used in the ink composition of the present invention at 0.01 to 0.5% by mass.

The pH of the ink composition for inkjet recording is preferably 6 to 11, and more preferably 7 to 10 from the viewpoints of improvement in print density and liquid stability. In order to bring the pH of the ink composition within the above range, it is preferable to contain a pH adjusting agent.
Examples of pH adjusters include inorganic alkalis such as sodium hydroxide, potassium hydroxide and lithium hydroxide, tertiary alcohols having 6 to 10 carbon atoms such as ammonia, triethanolamine, ethyldiethanolamine, diethylethanolamine and tripropanolamine. Examples include amines.
One or more pH adjusting agents can be used in the ink composition of the present invention, preferably at 0.01 to 2% by mass.

The inkjet recording method of the present invention includes a step of discharging the inkjet recording ink composition of the present invention onto a recording medium by an inkjet method.
The ink jet recording method of the present invention can use any method in which ink is ejected as droplets from a fine nozzle and the droplets are attached to a recording medium.

  Some of them will be explained. First, there is an electrostatic suction method. In this method, a strong electric field is applied between the nozzle and the acceleration electrode placed in front of the nozzle, ink is continuously ejected from the nozzle in the form of droplets, and a print information signal is output while the ink droplets fly between the deflection electrodes. There is a method of recording by applying to the deflection electrode, or a method of ejecting ink droplets corresponding to the print information signal without deflecting the ink droplets.

  The second method is a method in which ink droplets are forcibly ejected by applying pressure to the ink liquid with a small pump and mechanically vibrating the nozzle with a crystal resonator or the like. The ejected ink droplet is charged simultaneously with the ejection, and a printing information signal is given to the deflection electrode and recorded while the ink droplet flies between the deflection electrodes.

  The third method is a method using a piezoelectric element, in which pressure and a print information signal are simultaneously applied to ink with a piezoelectric element, and ink droplets are ejected and recorded.

  The fourth method is a method in which the ink is rapidly expanded in volume by the action of heat energy, and is a method in which the ink is heated and foamed with a microelectrode in accordance with a print information signal, and ink droplets are ejected and recorded.

  Any of the above methods can be used in an ink jet recording method using an ink composition. By applying the ink composition for ink jet recording of the present invention, excellent ejection stability and nozzle clogging prevention property can be realized in any ink jet recording system.

  The recording medium that can be used in the inkjet recording method of the present invention is not particularly limited, and a known recording medium can be used as a support or a recording material. For example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal (eg, aluminum, zinc, copper, etc.) plate, plastic (eg, cellulose diacetate, cellulose triacetate, propionic acid) Cellulose, butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), paper or plastic film on which the above-mentioned metal is laminated or deposited. .

  The recorded matter of the present invention is obtained by performing inkjet recording using at least the ink composition of the present invention. By using the ink composition of the present invention, the recorded matter improves the fixability of the ink composition, particularly the pigment in the ink composition, and has excellent density, scratch resistance, glossiness, characters, figures, etc. Images can be formed.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to the form in these Examples. Unless otherwise specified, “part” and “%” are based on mass.

<Measurement method of particle diameter in pigment dispersion>
The particle diameter in the pigment dispersion was measured using Nanotrac 150 (UPA-EX150) manufactured by Nikkiso Co., Ltd.

<Synthesis of Azo Pigment (1)>
The azo pigment (1), which is an azo pigment represented by the formula 1, was synthesized by the method described in JP 2010-159405 A. The length of the primary particles of the obtained azo pigment (1) in the major axis direction was about 0.2 μm.

<Production of pigment dispersion A>
10.0 parts of the azo pigment (1), 10.0 parts of EFKA 4585 (solid content concentration: ˜50%) manufactured by BSF, and 45.0 parts of water are mixed, and 375 parts of zirconia beads having a diameter of 0.1 mm. At the same time, dispersion was performed at 1,500 rpm and 45 ° C. using a sand grinder mill TSG1 (manufactured by Imex). After dispersion until the volume average particle diameter Mv was 100 nm or less, zirconia beads were separated to obtain 51 parts of pigment dispersion A having a pigment concentration of 15.2%.

<Production of pigment dispersion B>
10.0 parts of the azo pigment (1), DYPERBYK-181 (solid content concentration: ˜63%) manufactured by BYK Chemie Co., Ltd. and 47.2 parts of water are mixed, and 375 parts of zirconia beads having a diameter of 0.1 mm. At the same time, dispersion was performed at 1,500 rpm and 45 ° C. using a sand grinder mill TSG1 (manufactured by Imex). After dispersion until the volume average particle size Mv was 100 nm or less, zirconia beads were separated to obtain 57 parts of pigment dispersion B having a pigment concentration of 15.1%.

<Production of pigment dispersion C>
10.0 parts of the azo pigment (1), 6.3 parts of DISPERBYK-180 (solid content concentration: -79%) manufactured by Big Chemie, and 50.0 parts of water are mixed, and 375 parts of zirconia beads having a diameter of 0.1 mm. At the same time, dispersion was performed at 1,500 rpm and 45 ° C. using a sand grinder mill TSG1 (manufactured by Imex). After dispersion until the volume average particle diameter Mv was 100 nm or less, zirconia beads were separated to obtain 59 parts of pigment dispersion C having a pigment concentration of 14.9%.

<Manufacture of pigment dispersion D>
10.0 parts of the azo pigment (1), 9.6 parts of DISPERBYK-183 (solid content concentration: -52%) manufactured by Big Chemie, and 44.9 parts of water are mixed, and 375 parts of zirconia beads having a diameter of 0.1 mm. At the same time, dispersion was performed at 1,500 rpm and 45 ° C. using a sand grinder mill TSG1 (manufactured by Imex). After dispersion until the volume average particle diameter Mv became 100 nm or less, zirconia beads were separated to obtain 56 parts of pigment dispersion D having a pigment concentration of 15.3%.

<Manufacture of pigment dispersion E>
10.0 parts of the azo pigment (1), 9.6 parts of DISPERBYK-184 (solid content concentration: -52%) manufactured by BYK Chemie, and 46.0 parts of water are mixed, and 375 parts of zirconia beads having a diameter of 0.1 mm. At the same time, dispersion was performed at 1,500 rpm and 45 ° C. using a sand grinder mill TSG1 (manufactured by Imex). After dispersion until the volume average particle size Mv was 100 nm or less, zirconia beads were separated to obtain 59 parts of pigment dispersion E having a pigment concentration of 15.1%.

<Manufacture of pigment dispersion F>
10.0 parts of the azo pigment (1), 9.4 parts of EFKA 5071 (solid content concentration: 53%) manufactured by BSF, and 45.1 parts of water are mixed, and 375 parts of zirconia beads having a diameter of 0.1 mm. At the same time, dispersion was performed at 1,500 rpm and 45 ° C. using a sand grinder mill TSG1 (manufactured by Imex). After dispersion until the volume average particle size Mv was 100 nm or less, zirconia beads were separated to obtain 53 parts of pigment dispersion F having a pigment concentration of 15.4%.

<Manufacture of pigment dispersion G>
10.0 parts of azo pigment (1), 5 parts of SOLPERSE 27000 (solid content concentration: 100%) manufactured by Nippon Lubrizol Co., Ltd. and 51.2 parts of water are mixed together with 375 parts of zirconia beads having a diameter of 0.1 mm. Dispersion was performed at 1,500 revolutions per minute at 45 ° C. using a sand grinder mill TSG1 (manufactured by Imex). After the dispersion was performed until the volume average particle size Mv became 100 nm or less, zirconia beads were separated to obtain 57 parts of pigment dispersion G having a pigment concentration of 15.0%.

<Manufacture of pigment dispersion H>
10.0 parts of the azo pigment (1), 6.2 parts of DISPERBYK-2090 (solid content concentration: ~ 81%) manufactured by BYK Chemie, and 48.3 parts of water are mixed, and 375 parts of zirconia beads having a diameter of 0.1 mm. At the same time, dispersion was performed at 1500 rpm at 45 ° C. using a sand grinder mill TSG1 (manufactured by Imex). After dispersion until the volume average particle size Mv was 100 nm or less, zirconia beads were separated to obtain 55 parts of pigment dispersion H having a pigment concentration of 15.3%.

<Production of Pigment Dispersion I>
10.0 parts of the azo pigment (1), 9.1 parts of DISPERBYK-2091 (solid content concentration: ~ 55%) manufactured by BYK Chemie, and 48.0 parts of water are mixed, and 375 parts of zirconia beads having a diameter of 0.1 mm. At the same time, dispersion was performed at 1,500 rpm and 45 ° C. using a sand grinder mill TSG1 (manufactured by Imex). After dispersion until the volume average particle size Mv was 100 nm or less, zirconia beads were separated to obtain 58 parts of pigment dispersion I having a pigment concentration of 14.8%.

<Manufacture of pigment dispersion liquid J>
10.0 parts of the azo pigment (1), 12.5 parts of EFKA 4580 (solid content concentration: ˜40%) manufactured by BSF, and 43.2 parts of water are mixed, and 375 parts of zirconia beads having a diameter of 0.1 mm. At the same time, dispersion was performed at 1,500 rpm and 45 ° C. using a sand grinder mill TSG1 (manufactured by Imex). After dispersion until the volume average particle diameter Mv was 100 nm or less, zirconia beads were separated to obtain 58 parts of Pigment Dispersion Liquid J having a pigment concentration of 15.1%.

<Manufacture of pigment dispersion K>
10.0 parts of the azo pigment (1), 12.5 parts of EFKA 4560 (solid content concentration: ˜40%) manufactured by BSF, and 42.6 parts of water are mixed, and 375 parts of zirconia beads having a diameter of 0.1 mm. At the same time, dispersion was performed at 1,500 rpm and 45 ° C. using a sand grinder mill TSG1 (manufactured by Imex). After dispersion until the volume average particle size Mv was 100 nm or less, zirconia beads were separated to obtain 57 parts of pigment dispersion K having a pigment concentration of 15.2%.

<Production of Pigment Dispersion Liquid L>
10.0 parts of the azo pigment (1), 7.1 parts of DISPERBYK-187 (solid content concentration: -70%) manufactured by Big Chemie, and 48.5 parts of water are mixed, and 375 parts of zirconia beads having a diameter of 0.1 mm. At the same time, dispersion was performed at 1,500 rpm and 45 ° C. using a sand grinder mill TSG1 (manufactured by Imex). After dispersion until the volume average particle size Mv was 100 nm or less, zirconia beads were separated to obtain 54 parts of pigment dispersion L having a pigment concentration of 15.1%.

<Manufacture of pigment dispersion M>
10.0 parts of the azo pigment (1), 12.5 parts of DISPERBYK-190 (solid content concentration: ˜40%) manufactured by Big Chemie, and 42.9 parts of water are mixed, and 375 parts of zirconia beads having a diameter of 0.1 mm. At the same time, dispersion was performed at 1,500 rpm and 45 ° C. using a sand grinder mill TSG1 (manufactured by Imex). After dispersion until the volume average particle diameter Mv was 100 nm or less, zirconia beads were separated to obtain 58 parts of pigment dispersion M having a pigment concentration of 15.1%.

<Production of pigment dispersion N>
10.0 parts of azo pigment (1), 5 parts of SOLSPERSE 20000 (solid content concentration: 100%) manufactured by Nippon Lubrizol Co., Ltd. and 50.0 parts of water are mixed together with 375 parts of zirconia beads having a diameter of 0.1 mm. Dispersion was performed at 1,500 revolutions per minute at 45 ° C. using a sand grinder mill TSG1 (manufactured by Imex). After dispersion until the volume average particle diameter Mv was 100 nm or less, zirconia beads were separated to obtain 53 parts of pigment dispersion N having a pigment concentration of 15.3%.

<Manufacture of pigment dispersion liquid O>
10 parts of the azo pigment (1), 3 parts of sodium oleate, 10 parts of glycerin and 77 parts of water are mixed together with 375 parts of zirconia beads having a diameter of 0.1 mm using Sand Grinder Mill TSG1 (manufactured by IMEX). Dispersion was performed at 1,500 rpm for 45 ° C. After dispersion until the volume average particle size Mv was 100 nm or less, zirconia beads were separated to obtain 78 parts of Comparative Pigment Dispersion Liquid 1 having a pigment concentration of 9.9%.

Example 1
<Production of pigment dispersion 1>
While stirring 6.6 parts of Pigment Dispersion A, slowly add 6.6 parts of Pigment Dispersion B, and then add 6.4 parts of water to add a pigment concentration of 10.2%. Liquid 1 was obtained.

(Examples 2 to 15)
<Production of pigment dispersions 2 to 15>
Pigment dispersions 2 to 15 were prepared in the same manner as in the preparation of pigment dispersion 1 and in combination as described in Table 2 below.

(Example 16)
<Manufacture of pigment dispersion liquid 16>
Pigment dispersion 1 was heated at 60 ° C. for 1 hour to obtain pigment dispersion 16.

(Example 17)
<Manufacture of pigment dispersion liquid 17>
4 parts of ion exchange resin (Amberlite MB-2 manufactured by Organo Corporation) was added to 80 parts of pigment dispersion 1, and the mixture was stirred for about 4 hours, and then the ion exchange resin was removed. Thereafter, triisopropanolamine (manufactured by Wako Pure Chemical Industries, Ltd.) was added to adjust the pH to 9.0 to obtain a pigment dispersion liquid 17.

(Example 18)
<Manufacture of pigment dispersion liquid 18>
4 parts of ion exchange resin (Amberlite MB-2 manufactured by Organo Corporation) was added to 80 parts of pigment dispersion 2, and the mixture was stirred for about 4 hours, and then the ion exchange resin was removed. Thereafter, triisopropanolamine (manufactured by Wako Pure Chemical Industries, Ltd.) was added to adjust the pH to 9.0 to obtain a pigment dispersion 18.

(Comparative Example 1)
Comparative pigment dispersion 1 was obtained in the same manner except that azo pigment (1) was replaced by pigment yellow (PY) 74 in the production of pigment dispersion 1.

<Pigment ink I>
Water was added to each of the pigment dispersions 1 to 18, the comparative pigment dispersion 1 and the pigment dispersions A to O of the above examples so that the total weight was 10.88 parts and the pigment concentration was 6.90%. , There are 0.45 parts 2-pyrrolidinone, 2.25 parts glycerol, 0.60 parts 1,2-hexanediol, 0.75 parts ethylene glycol, Surfynol 465 (surfactant, Nissin Chemical Industry Co., Ltd.) ) Made by adding 0.08 parts of the mixed solution, stirring sufficiently, pigment inks I-1 to I-18 having a pigment concentration of 5% by weight, comparative pigment ink I-1 and pigment inks IA to IO Got.

<Pigment ink II>
Water was added to each of the pigment dispersions 1 to 18, the comparative pigment dispersion 1 and the pigment dispersions A to O of the above examples so that the total weight was 11.15 parts and the pigment concentration was 6.73%. Then, 1.50 parts of triethylene glycol monobutyl ether, 2.25 parts of ethylene glycol and 0.11 part of Surfinol 485 (surfactant, manufactured by Nissin Chemical Industry Co., Ltd.) were added and fully The mixture was stirred to obtain pigment inks II-1 to II-18, comparative pigment ink II-1 and pigment inks II-A to II-O having a pigment concentration of 5% by mass.

[Evaluation]
<Storage stability (viscosity and pH)>
Pigment dispersions 1 to 18, pigment dispersion 1 of comparative example, pigment dispersions A to O, pigment inks I-1 to I-18, comparative pigment ink I-1, pigment inks IA to IO Pigment inks II-1 to II-18, Comparative pigment ink II-1 and Pigment inks II-A to II-O were each allowed to stand at 60 ° C. for 4 weeks.

-Viscosity-
Regarding the viscosity of pigment dispersions and pigment inks that have been allowed to stand for 4 weeks, the change rate of the viscosity before and after 4 weeks of standstill is within 5%, A is more than 5% and less than 10%, and B is 10% or more. Evaluation was made with C less than 15% and D with 15% or more. The viscosity of each pigment dispersion and pigment ink was measured using a RE80L viscometer manufactured by Toki Sangyo Co., Ltd. under the conditions of 25 ° C. and 100 rpm.

-PH-
Changes in pH of the pigment dispersion and the pigment ink that were allowed to stand for 4 weeks were A when the pH was less than 0.5, B when 0.5 or less and less than 1, C when 1.5 or less and less than 1.5. The above was evaluated as D.

-Particle size-
Measure the volume average particle size of the pigment dispersion and pigment ink before and after standing for 4 weeks (measured using Nanotrac 150 (UPA-EX150) manufactured by Nikkiso Co., Ltd.) Change in volume average particle size before and after standing for 4 weeks A with a rate of 10% or less, B with a rate of change exceeding 10% and less than 15%, C with a rate of change of 15% to less than 20%, and D with a rate of change of 20% or more As evaluated.

<Image robustness>
The water-based ink is a yellow ink, and an optical density (OD) is set to 1.0 on a photographic paper image manufactured by Fuji Film Co., Ltd. using a commercially available ink jet printer (model number: PX-V630) manufactured by Seiko Epson Corporation. Then, the image was irradiated with xenon light (100,000 lux) for 2 weeks using a weather meter manufactured by Atlas. The OD before and after the test was measured with X-Rite 310 (manufactured by X-Rite), and the residual ratio of OD was determined and evaluated. The residual ratio was evaluated as A for 90% or more, B for less than 90% and 80% for C, and C for less than 80%.

  The evaluation results are summarized in Table 3.

[Synthesis of Fine Azo Pigment (1)]
The obtained azo pigment (1) was subjected to salt milling to obtain a fine azo pigment (1) having a primary particle length of 0.03 μm. Salt milling was performed by the following method.
The azo pigment (1) and sodium chloride were put into a supermixer and mixed so as to have the following composition. Diethylene glycol was added little by little while rotating the supermixer to prepare a mixture (hereinafter sometimes referred to as “preliminary mixture”).
-Azo pigment (1)-150 parts-Salt (Oshiomicron T-0 manufactured by Ako Kasei Co., Ltd.)-1,500 parts-Diethylene glycol-300 parts Subsequently, a continuous uniaxial kneader ( Asada Iron Works Co., Ltd., Miracle KCK-L), the temperature of 5 parts of the grinding part and the extrusion part is set to 15-20 ° C., the shaft rotation speed is set to 50 rpm, the preliminary mixture obtained above is charged, A kneaded product was obtained. At this time, the current value (load) was about 4 A, the discharge rate was 50 g / min, and the temperature of the discharged material was 16 ° C.
The kneaded product thus obtained was added to 5,000 parts of 1% dilute hydrochloric acid and stirred, and then filtered and washed thoroughly with water to remove salt and diethylene glycol, followed by drying, and a fine azo pigment (1) Got.

  In the production of pigment dispersions A to N, pigment dispersions A ′ to N ′ were similarly prepared as shown in Table 4 using the fine azo pigment (1) instead of the azo pigment (1). Further, pigment dispersions 101 to 107 were prepared in combinations shown in Table 5. The evaluation results of storage stability and image fastness are shown in Table 6.

<Manufacture of pigment dispersion 108>
4 parts of an ion exchange resin (Amberlite MB-2 manufactured by Organo Corporation) was added to 80 parts of the pigment dispersion 101 and stirred for about 4 hours, and then the ion exchange resin was removed. Thereafter, triisopropanolamine (manufactured by Wako Pure Chemical Industries, Ltd.) was added to adjust the pH to 9.0 to obtain a pigment dispersion 108.

  Even if the fine azo pigment (1) was used, good results were obtained. Whether the azo pigment (1) not subjected to salt milling or the fine azo pigment (1) subjected to salt milling is used, the aqueous pigment dispersion of the present invention and the pigment ink using the same are as follows: The performance was equivalent.

Claims (15)

Step a in which an azo pigment represented by Formula 1 or a tautomer thereof, and a first dispersant are dispersed in water to obtain an aqueous pigment dispersion A,
A step b in which an azo pigment represented by Formula 1 or a tautomer thereof, and a second dispersant are dispersed in water to obtain an aqueous pigment dispersion B; and
A process c for producing an aqueous pigment dispersion, comprising the step c of mixing the aqueous pigment dispersion A and the aqueous pigment dispersion B to obtain an aqueous pigment dispersion.

  The method for producing an aqueous pigment dispersion according to claim 1, wherein at least one of the first dispersant and the second dispersant is a polymer dispersant. The first dispersant is a dispersant having an amine value of 5 mgKOH / g or more and an amine value> acid value,
The method for producing an aqueous pigment dispersion according to claim 1 or 2, wherein the second dispersant is a long-chain fatty acid salt or a dispersant having an acid value of 5 mgKOH / g or more and an acid value ≥ amine value.   The manufacturing method of the aqueous pigment dispersion liquid of any one of Claims 1-3 including the process of heat-processing with respect to the obtained aqueous pigment dispersion liquid after the process c.   In the obtained aqueous pigment dispersion, the total content of the first dispersant and the second dispersant is 10 with respect to 100 parts by mass of the azo pigment represented by Formula 1 or a tautomer thereof. The manufacturing method of the aqueous pigment dispersion liquid of any one of Claims 1-4 which is -80 mass parts.   The method for producing an aqueous pigment dispersion according to any one of claims 1 to 5, wherein the azo pigment represented by Formula 1 or a tautomer thereof is not subjected to salt milling.   The aqueous pigment dispersion liquid manufactured by the manufacturing method of the aqueous pigment dispersion liquid of any one of Claims 1-6.   The coloring composition using the aqueous pigment dispersion manufactured by the manufacturing method of the aqueous pigment dispersion of any one of Claims 1-6 as a raw material.   An ink composition using, as a raw material, an aqueous pigment dispersion produced by the method for producing an aqueous pigment dispersion according to any one of claims 1 to 6.   The ink composition according to claim 9, which is an ink composition for inkjet recording.   An ink jet recording method comprising a step of discharging the ink composition for ink jet recording according to claim 10 onto a recording medium by an ink jet method. An azo pigment represented by Formula 1 or a tautomer thereof;
A first dispersant;
A second dispersant;
And an aqueous pigment dispersion characterized by containing water.

  The aqueous pigment dispersion according to claim 12, wherein at least one of the first dispersant and the second dispersant is a polymer dispersant. The first dispersant is a dispersant having an amine value of 5 mgKOH / g or more and an amine value> acid value,
The aqueous pigment dispersion according to claim 12 or 13, wherein the second dispersant is a long-chain fatty acid salt or a dispersant having an acid value of 5 mgKOH / g or more and an acid value ≥ amine value.   The total content of the first dispersant and the second dispersant is 10 to 80 parts by mass with respect to 100 parts by mass of the azo pigment represented by Formula 1 or a tautomer thereof. Item 15. The aqueous pigment dispersion according to any one of Items 12 to 14.